Nonlinear dynamics in nanomechanical oscillators

In the present work we investigate nonlinear dynamics in a nanomechanical doubly clamped beam made of PdAu fabricated using bulk nanomachining and e-beam lithography. The beam is driven into nonlinear regime of oscillations and the response is measured by an electron beam displacement detector. In one set of experiments we study the impact of nonlinear damping on the dynamics in the bistable regime of operation. For data analysis we introduce a nonlinear damping term to Duffing equation. The experiment shows conclusively that accounting for nonlinear damping effects is needed for correct modeling of the dynamics. In another set of experiments we study intermodulation mechanical gain near the onset of bistability. As predicted by a theoretical analysis, we find high intermodulation gain when the system is operated close to a bifurcation.